Terms of Reference

State of Knowledge on the Natural Attenuation of Oil in Canadian Environments

National Peer Review - National Capital Region

February 5-8, 2024

Virtual Meeting

Chairpersons: Shauna Baillie and David Cooper

Context

Under Canada’s Oceans Protection Plan (OPP), DFO significantly advanced its role within Canada’s spill response regime. Over the past 5 years, DFO has leveraged funding to Canadian and international research teams to support scientific, technological and strategic advancements in oil spill preparedness and response to minimize the environmental impacts of oil. In particular, two initiatives – 1) Research on Fate, Behavior and Biological Impacts of Oil, and 2) the Multi-Partner Research Initiative (MPRI) – enhanced scientific knowledge in oil spill response to support science-based decision making. Both initiatives have contributed to improving the knowledge base for the selection and use of traditional methods and/or ARMs to mitigate oil spills in the marine environment. While much of the DFO-supported research on natural attenuation has been published in academic journals there is still a need to consolidate it and other technical research into formal scientific advice that will enhance DFO’s ability to support incident response and recovery.

For the purposes of this research document, natural attenuation is defined as any physical, chemical or biological process that, under favourable conditions, act without human intervention to reduce the mass toxicity, mobility, volume or concentration of petroleum hydrocarbons from oil spills in the marine environment. In this context, the marine environment includes all marine habitats within the EEZ from the high intertidal to the open ocean and all depths Natural attenuation processes include: biodegradation, dispersion, dilution, sorption, volatilization, photodegradation and chemical or biological stabilization, transformation, or destruction of petroleum hydrocarbons (Definition modified from USEPA Remedial Technology Fact Sheet, 1999).

DFO has hired PGL Environmental Consultants Ltd. to synthesize and analyze scientific and technical literature relating to the current state of knowledge on the natural attenuation of oil relevant to the Canadian environment into a working paper.

Objectives

The goal of this science peer review is to enhance awareness, assess and critically evaluate the state of knowledge on natural attenuation in a Canadian context. This review will document robust, scientific advice and recommendations that will then be available for use to inform future initiatives and decision-making processes involved in the operational response regime at a national level.

More specifically, the outcomes from this process are expected to: inform critical and time sensitive spill response decisions; communicate how the best available scientific information is integrated into spill response decisions; reduce the potential for adverse effects on aquatic ecosystems; inform the development of policy and regulatory processes; support the development of operational guidance; and support various Government of Canada initiatives related to spill response.

Specific questions to be addressed at the meeting include:

1. How do different oils naturally attenuate? How do physical, chemical and biological processes affect oil attenuation in the marine environment? How would natural attenuation differ for surface spills vs deep water releases? What conditions (environmental and/or operational) are optimal for natural attenuation to be considered as a response option?
2. What are the potential impacts to Canadian marine species and ecosystems (subarctic vs arctic, shoreline vs open ocean) if oil is allowed to naturally attenuate as an operational spill response measure? Consider short and long term effects over a range of oils from light to heavy.
3. How can natural attenuation be stimulated or enhanced (e.g., through the addition of nutrients, oxygen, etc.)?
4. How do traditional response measures (e.g. booming, skimming) and alternative response measures (dispersants, in-situ burning, surface washing agents) affect natural attenuation?
5. What resources are accessible such as models, frameworks, or case studies with long-term monitoring data (Exxon Valdez, Arrow, etc.) to inform responders during an incident on natural attenuation as an operational spill response measure?
6. What are the outstanding science needs to inform decisions on natural attenuation as a response option in Canada?

Expected Publications

• Science Advisory Report
• Research Document

Expected Participation

• Fisheries and Oceans Canada (DFO) (e.g., Ecosystems and Oceans Science, and Ecosystems and Fisheries Management)
• Other Federal Government experts (e.g. Canadian Coast Guard, Natural Resources Canada, and Environment and Climate Change Canada)
• Academia
• Industry
• Other invited experts